In July 2011, Unilever Turkey launched the ‘Sustainable Tea Agriculture’ project with an aim that consumers in Turkey would soon be able to buy Lipton tea bearing the Rainforest Alliance™ seal on the pack. The final objective was that by 2018, all Lipton teas sold in Turkey would be sourced from Rainforest Alliance™ Certified farms. This case describes the measures taken so far to achieve the above initiative, and also the challenges that were expected in convincing Lipton Tea consumers and supply chain collaborators of the real value proposition of such sustainability efforts. Through this case, students would be exposed to the concept of sustainability, and to the many factors that have made it become so important for companies, particularly the large multi-nationals, to commit to such initiatives.

In this paper, we focus on top-k queries with linear preference functions over the queried dimensions. We codify the conditions under which changes in a dimension’s weight invalidate the query result, and develop algorithms to compute the immutable regions. In general, this entails the examination of numerous non-result tuples. To reduce processing time, we introduce a pruning technique and a thresholding mechanism that allow the immutable regions to be determined correctly after examining only a small number of non-result tuples. We demonstrate empirically that the two techniques combine well to form a robust and highly resource-efficient algorithm. We verify the generality of our findings using real highdimensional data from different domains (documents, images, etc) and with different characteristics.